This invention relates generally to clothes dryers and, more specifically, to control algorithms for clothes dryers.
An appliance for drying articles such as a clothes dryer typically includes a cabinet including a rotating drum for tumbling clothes and laundry articles therein. One or more heating elements heat air prior to the air entering the drum. The warm air is circulated through the drum as the clothes and laundry items are tumbled to remove moisture from the articles in the drum.
At least one known clothes dryer utilizes an open loop control system to determine an appropriate amount of time for drying a load of clothes. The drying time is determined by an operator and entered using a manual control, such as a time selector switch. For the duration of the drying time, the heating elements are activated and deactivated to maintain warm air circulation inside the drum, and for more accurate control of the dryer heating elements, a temperature sensor is sometimes used in conjunction with the heating elements. The operator selects a drying time based on the desired dryness for the clothes and based on past experience with the particular machine. A longer drying time than is necessary to fully dry the clothes is commonly selected to ensure that the clothes are fully dried. Use of more time than is needed for effective drying, however, is wasteful.
On at least some known dryers, the heating elements are often turned completely off to maintain air temperature below a maximum allowable temperature, while the blower on known residential dryers is driven at a constant speed for the total drying time. These approaches may not facilitate lowering drying time, improving dryer efficiency, or reducing electrical energy consumption.